This invention relates to shell cutters, and in particular it relates to a shell cutter having new and improved cutting assemblies.
Shell cutters are known for cutting holes into existing pipelines, at a direction perpendicular to the existing pipeline, for the purpose of attaching an additional perpendicular pipeline onto the existing pipeline. An example of a previously known shell cutter of this general type is shown in the Howe U.S. Pat. No. 563,488, issued July 7, 1896. The Daghe et al U.S. Pat. No. 4,057,357, issued Nov. 8, 1977, shows a shell cutter of this general type but adapted especially for cutting plastic pipe.
A shell cutter adapted for use on all pipeline materials, including plastic, steel or cast iron, must of course be sufficiently strong for cutting the latter. Moreover, it is important that such a shell cutter have a plurality of cutting teeth so that the cutting action is balanced. Heretofore, in a shell cutter having a plurality of teeth and suitable for heavy duty use on pipes made of steel, cast iron or the like, the cutting teeth have been carbide teeth which have been brazed directly onto the end of the rotating cylinder which forms the body of the shell cutter. When the carbide teeth become broken or dulled, the entire cutter must be taken off of the machine and taken to a repair shop whereat all of the teeth must be replaced. The teeth are then ground on the inside diameter, the outside diameter, and on the top, and the proper cutting clearance is provided on the front of the cutter so it can be used again. This procedure is not only expensive, but it is quite time consuming, often taking several days. Hence, the operator must either delay the pipe cutting job for several days or invest in a backup cutting device. Either alternative involves additional costs.
Hence, there exists a need for a multi-toothed, heavy duty shell cutter wherein the above noted disadvantages are overcome.